Genome-wide linkage analysis combined with genome sequencing in large families with intracranial aneurysms

Genetic Insights Into Hemorrhagic Stroke and Vascular Malformations: Pathogenesis and Emerging Therapeutic Strategies

Brain arteriovenous malformations (AVMs), cerebral cavernous malformations (CCMs), and intracranial aneurysms are major causes of hemorrhagic stroke, yet noninvasive therapies to prevent growth or rupture are lacking. Understanding the genetic basis of these malformations is critical for uncovering underlying mechanisms, developing targeted prevention strategies, and identifying novel therapeutic targets. This review highlights the causal genes and signaling pathways in AVMs, CCMs, and intracranial aneurysms, noting both their commonalities and differences. For AVMs, somatic mutations in the RAS (rat sarcoma virus)/MAPK (mitogen-activated protein kinase) and MAPK/ERK (extracellular signal-regulated kinase) pathway are key, particularly in sporadic cases, whereas hereditary conditions like hereditary hemorrhagic telangiectasia and capillary malformation-AVM involve the TGF-β (transforming growth factor β), Ephrin receptor, and angiopoietin-VEGF (vascular endothelial growth factor) signaling pathways. In CCMs, pathways affecting endothelial junctions and vascular stability, such as the ROCK (RhoA/Rho-associated coiled-coil containing kinases) pathway, play a central role. Although the genetic drivers of intracranial aneurysms are more diverse and less clearly linked to specific pathways, there is some overlap with genes in the TGF-β and endothelial function pathways seen in AVMs and CCMs. Emerging therapies for AVMs and CCMs include MAPK/ERK inhibitors, anti-VEGF treatments, and RhoA/ROCK inhibitors, showing potential in preclinical models. Due to the genetic overlap, these advancements may also offer future therapeutic strategies for intracranial aneurysms. As personalized medicine progresses, the development of reliable biomarkers, such as the candidate biomarker VEGF for AVMs and CCMs, will be crucial for guiding treatment decisions. In conclusion, ongoing research into genetic pathways holds promise for novel therapeutic targets that could transform the management of vascular malformations and reduce the risk of hemorrhagic stroke.

Rare genetic variants in PKD1 and SMAD2 are associated with intracranial aneurysms in the general population

INTRODUCTION

Family studies identified several rare genetic risk variants for intracranial aneurysms (IAs) and aneurysmal subarachnoid hemorrhage (ASAH). In addition, certain monogenic disorders caused by rare penetrant genetic variants predispose individuals to IA and ASAH. We investigated the effect of these variants on IA and ASAH in the general population.

PATIENTS AND METHODS

We tested the association between genetic variants within IA-associated genes and IA and ASAH using a burden test, sequence kernel association test (SKAT), and variant-level aggregated Cauchy association test (ACAT-V) in the UK Biobank. Variants were stratified by allele frequency and predicted impact on the protein structure. Sensitivity analyses were performed on only ASAH patients and excluding participants diagnosed with an aforementioned monogenic disorder.

RESULTS

In the group of 1656 IA cases, including 928 ASAH cases, and 391,948 controls, associations were identified for ultrarare variants with moderate or high impact in PKD1 (odds ratio (OR) = 1.42; 95% confidence interval (95% CI)= 1.06-1.85, p = 4.28 × 10-7 (SKAT)) and SMAD2 (OR = 4.89; 95% CI = 1.63-11.05, p = 7.10 × 10-5 (SKAT)). Upon excluding participants diagnosed with the respective monogenic disorders, these associations remained. When considering only ASAH cases, the association with SMAD2 was similar (OR = 4.85; 95% CI = 1.02-13.7; p = 9.0 × 10-4) while for PKD1 the association diminished (OR = 1.29; 95% CI = 0.85-1.87; p = 0.043).

DISCUSSION AND CONCLUSION

Ultrarare damaging variants in PKD1, a gene causing autosomal dominant polycystic kidney disease, and SMAD2, a gene causing Loeys-Dietz syndrome, were associated with IA in the general population, even in the absence of a diagnosis of these disorders. Our results may contribute to the development of genetic screening methods for IA in a clinical setting.

Genetic Overlap of Thoracic Aortic Aneurysms and Intracranial Aneurysms

OBJECTIVE

Thoracic aortic aneurysms (TAAs) and intracranial aneurysms (ICAs) share overlapping genetic and pathophysiological mechanisms, yet the genetic interplay between these conditions remains insufficiently explored. This study aimed to identify common genetic factors underlying TAA and ICA.

METHODS

A comprehensive review of genome-wide association studies (GWASs) and retrospective clinical studies was conducted using PubMed, Orbis, and Web of Science. Articles addressing the genetic etiologies of TAA and ICA were analyzed. Separate lists of causative genes were compiled, and commonalities were identified. A Venn diagram was constructed to illustrate genetic overlap and shared physiological pathways.

RESULTS

We identified 24 overlapping genes associated with TAA and ICA, including LTBP2, TGFB2, TGFB3, TGFBR1, TGFBR2, SMAD2, SMAD3, COL1A2, COL3A1, COL4A1, COL5A1, COL5A2, FBN1, FBN2, ELN, LOX ACTA2, MYH11, MYLK, ABCC6, NOTCH1, MED12, PKD1, and PKD2. These genes are involved in pathways related to connective tissue biology, contractile elements, extracellular matrix components, and transforming growth factor-β signaling. While vascular endothelium and cell cycle pathways were unique to ICA, TAA pathways predominantly involved extracellular matrix remodeling.

CONCLUSIONS

This study highlights the significant genetic overlap between TAA and ICA, shedding light on shared molecular mechanisms. These findings underscore the importance of interdisciplinary awareness: neurologists, neurosurgeons, and neurointerventional radiologists should monitor ICA patients for potential TAA, while cardiologists, cardiac surgeons, vascular surgeons, and vascular interventionalists should consider ICA risks in TAA patients. Further research into these genetic pathways could enhance the understanding and management of both conditions.

Genetic Insights into the Enigma of Family Intracranial Aneurysms

Familial intracranial aneurysms (FIAs) are distinguished by significant genetic predisposition, leading to clustering of cases within families and heightening the risk of subarachnoid hemorrhage following aneurysm rupture. This review analyzes recent advancements in understanding the genetic and molecular mechanisms underlying FIAs, focusing on key genetic risk factors and environmental influences. We explore cutting-edge genome-wide association studies and next-generation sequencing technologies, which have identified susceptibility genes such as ANGPTL6, peptidyl proline cis-trans isomerase like protein 4, and NOTCH3 as crucial contributors to FIA pathophysiology. By incorporating findings from multiomics and gene-editing research, we highlight the potential for improved screening, preventive strategies, and therapeutic approaches. These insights are essential to advancing precision medicine in managing FIAs, paving the way for collaborative research and targeted interventions.

Appraising the causal association among depression, anxiety and intracranial aneurysms: Evidence from genetic studies

BACKGROUND

The risk of intracranial aneurysms (IAs) is increased in individuals with depression and anxiety. This indicates that depression and anxiety may contribute to the development of physical disorders. Herein, to investigate the association between genetic variants related to depression and anxiety and the risk of IA, two-sample Mendelian randomization was performed.

METHODS

The genome-wide association study (GWAS) comprised genome-wide genotype data of 2248 clinically well-characterized patients with anxiety and 7992 ethnically matched controls from four European countries. Sex-specific summary-level outcome data were obtained from the GWAS of IA, including 23 cohorts with a total of 10,754 cases and 306,882 controls of European and East Asian ancestry. To improve validity, five varying Mendelian randomization techniques were used in the analysis, namely Mendelian randomization-Egger, weighted median, inverse variance weighted, simple mode, and weighted mode.

RESULTS

The inverse variance weighted results indicated the causal effect of depression on IA (P = 0.03, OR = 1.32 [95 % CI, 1.03-1.70]) and unruptured IA (UIA) (P = 0.02, OR = 1.68 [95 % CI, 1.08-2.61]). However, the causal relationship between depression and subarachnoid hemorrhage (SAH) was not found (P = 0.16). We identified 43 anxiety-associated single-nucleotide polymorphisms as genetic instruments and found no causal relationship between anxiety and IA, UIA, and SAH.

LIMITATIONS

Potential pleiotropy, possible weak instruments, and low statistical power limited our findings.

CONCLUSION

Our MR study suggested a possible causal effect of depression on the increased risk of UIAs. Future research is required to investigate whether rational intervention in depression treatment can help to decrease the societal burden of IAs.